What about a .223 or .22-250?
I've hunted roe deer extensively in the UK and the .22 centerfire is allowed in Scotland but not in the remainder of the UK. As I'm now a citizen of the USA, I can admit to shooting more than a few of them with a .22 Hornet at under 50 yards with complete satisfaction and very little meat damage. I wouldn't say you would be undergunned with either the .223 or the .22-250 but if you wanted to shoot any other species, you might be.
The most common caliber for roe and other species aside from red deer in the UK is the .243. In my experience, the .270 is very popular for red, sika, fallow et al with .308/.30-06 not far behind. Looks like a stunning place to hunt!
